Japan has quarantined a cruise ship carrying more than 3,700 people after one tested positive for the Wuhan coronavirus last week.

An unnamed 80-year-old man boarded The Diamond Princess in Yokohama on January 20, disembarked in Hong Kong on January 25, and admitted himself to the hospital on January 31. He was deemed to have contracted the virus.

The cruise ship, operated by Carnival Japan, arrived back to Yokohama on Monday. It was placed under quarantine upon arrival, Reuters reported.

Map showing Yokohama, Japan, where The Diamond Princess passengers boarded and are meant to disembark; and Hong Kong, where the infected passenger disembarked on January 25 and was later tested positive for the Wuhan coronavirus.

Those displaying any signs of the virus, including high temperatures and fevers, would undergo further tests from medical staff, Japan's Chief Cabinet Secretary Yoshihide Suga said, according to The Japan Times.

Guests were allowed to resume their onboard activity after being screened, but the casino, shops, and photo studio have been shut, Reuters reported. It's not entirely clear what the other activities available are.

A passenger on board has been tweeting images of the ship amid the quarantine. They show heavily-protected medical workers in blue walking up and down the deserted hallways, and once-populated attractions - like the rooftop pool - totally empty.